# PiBoSo Official Forum

## World Racing Series => Cars => Mods => Physics => Topic started by: Phathry25 on December 22, 2015, 01:15:53 AM

Title: Suspension
Post by: Phathry25 on December 22, 2015, 01:15:53 AM
What position should the suspension be in when measurements are taken?

What is spindle position?  How is it measured?

What is shockminlength?  RestLength? (in CFG file)

Is there a setting so I can have my tie links in front of the spindle?  When I try right now I get reversed steering.

Guessing by the other cars the bottom of the car should be at 0 in the scene.  Suspension in full droop?  At desired base ride height?  Fully compressed?
Title: Re: Suspension
Post by: Obelix90 on December 22, 2015, 01:31:55 PM
Hi Phathry,
to have the tie links in front of the spindle, there is an option in the .cfg file.
`steer{ racklength = 0.095 rackdirection = 1 ratio { range = 695, 0, 695 setting = 0 } lock = 28.5}`
I think, rackdirection=1 or 0 should solve your problem.

I'm not sure, but I think the shockminlength is the lentgh of the shock, when it is fully compressed(minimum distance between the two red points in the debug mode). The distance which the shock can travel should be the restlength.

I'm also interested in this information, so I hope somebody could tell more. :)

Title: Re: Suspension
Post by: Phathry25 on December 23, 2015, 03:56:45 AM
Thanks for the help.  I redid my GEOM file with the information provided, and the steering was correct, but the shock information still doesn't jive.

In the example cars, rest length is always shorter than min length.

Guess I'll just have to hunker down and wait for the boss to get to me.
Title: Re: Suspension
Post by: PiBoSo on December 23, 2015, 10:51:38 AM

"shock_minlength" is added to the spring / damper length and to ride height to calculate, in realtime, the distance between the two shock links.
Title: Re: Suspension
Post by: Phathry25 on December 23, 2015, 05:13:33 PM
So we're clear.

I build the car with all the suspension bits fully compressed and then add everything from there, right?

What is shock rest length then?
Title: Re: Suspension
Post by: Phathry25 on December 24, 2015, 06:20:25 PM
Built my car with the suspension fully compressed and got the suspension to rebound and set its ride heights correctly, but it compresses way too much. Like the tops of the wheels will touch with a big enough impact.

What am I missing? Where did I go wrong?
Title: Re: Suspension
Post by: Phathry25 on December 27, 2015, 11:29:16 PM
Anyone?
Title: Re: Suspension
Post by: Obelix90 on December 27, 2015, 11:32:52 PM
Title: Re: Suspension
Post by: Phathry25 on December 28, 2015, 03:20:53 AM
Spring should be irrelevant, I am trying to hit the bump stops after all.

Raising the minlength values just pushes the shock_bodylinks higher.  It doesn't seem to effect travel in either direction.  RestLength is for sure the amount of rebound travel.

I was looking at it as minlength is the absolute minimum length between the two points, or where the bump stop should be, it's not.  Or I have something else messed up.  My best guess after tweaking everything every which way is that travel is limited by the distance between the two shock mounting points.  But I know that's not right either because I did some testing with the F2000, and while the distance between the two shock mounts is pretty long, it doesn't travel upwards much, but does travel downwards about 2 feet.
Title: Re: Suspension
Post by: Obelix90 on January 01, 2016, 07:21:18 PM
Hi,
I also have a problem with the suspension. When the car is standing still, the front suspension compresses to much (about half of spring lentgh). It makes no big difference, if I set the spring to 75 N/mm or 10000! N/mm but when I jump the suspension decompresses to the maximum length. I'm using the MacPherson suspension like the FMK. Is this the same problem you like yours, Phathry?

What type of suspension do you use?

Quote from: Phathry25 on December 28, 2015, 03:20:53 AM
Raising the minlength values just pushes the shock_bodylinks higher.
The shock_bodylink is a attached to the chassis. How could it be pushed upwards?

Edit:
Quote from: PiBoSo on December 23, 2015, 10:51:38 AM
"shock_minlength" is added to the spring / damper length and to ride height to calculate, in realtime, the distance between the two shock links.
spring / damper length is RestLength, right?
Title: Re: Suspension
Post by: Phathry25 on January 01, 2016, 09:46:21 PM
I have a double wishbone at the front with 16" of travel. My ride heights look about right and so does my droop travel, it's just that I can't hit the bump stops. Maybe I'll just set the packers super long until I can get the desired amount of compression travel.
Title: Re: Suspension
Post by: Obelix90 on January 03, 2016, 09:50:43 AM
I found my mistake. I forgot to change the KeeperSpring value in the .CFG file. Now it works much better.
Title: Re: Suspension
Post by: Phathry25 on February 03, 2016, 03:50:40 AM
Quote from: PiBoSo on December 23, 2015, 10:51:38 AM

"shock_minlength" is added to the spring / damper length and to ride height to calculate, in realtime, the distance between the two shock links.

What is rest length?
Title: Re: Suspension
Post by: PiBoSo on February 03, 2016, 12:39:45 PM
Quote from: Phathry25 on February 03, 2016, 03:50:40 AM
Quote from: PiBoSo on December 23, 2015, 10:51:38 AM

"shock_minlength" is added to the spring / damper length and to ride height to calculate, in realtime, the distance between the two shock links.

What is rest length?

The length difference between the uncompressed and fully compressed spring.
Title: Re: Suspension
Post by: Phathry25 on February 03, 2016, 08:39:24 PM
I hate to be a bother, but I want to be sure I am doing this right.

I define my suspension in the GEOM file as it would sit fully compressed. Ride height is added from there. Shock min length is the minimum distance between the two shock mounting points, rest length is then added to shock min length to get your maximum downwards travel.

Or no?
Title: Re: Suspension
Post by: HornetMaX on February 03, 2016, 09:40:47 PM
Someone once said that one image is worth a thousand words.
Title: Re: Suspension
Post by: PiBoSo on February 03, 2016, 11:38:10 PM
Quote from: Phathry25 on February 03, 2016, 08:39:24 PM
I hate to be a bother, but I want to be sure I am doing this right.

I define my suspension in the GEOM file as it would sit fully compressed. Ride height is added from there. Shock min length is the minimum distance between the two shock mounting points, rest length is then added to shock min length to get your maximum downwards travel.

Or no?

Correct, but you should also add ride height.
Title: Re: Suspension
Post by: Phathry25 on February 09, 2016, 02:12:26 AM
Here are my measurements in the real world/max.

ShockMinLength, length between body mount and lower arm mount at full compression travel.  0.476m
RestLength, length between body mount, and lower arm mount at full droop travel.  0.7m
RideHeight, distance from the bottom of the frame to the ground.  0.254m

Entering these measurements into the game nets this really awesome result.
(https://i.gyazo.com/b298111f36e5399bd90e75193fe6dc63.png)

Setting right height to 0 gets you this result.
(https://i.gyazo.com/ed20507bc7cdb5da8014cd43150362f8.png)

Showroom settings...
`[SHOWROOM]flsusp_length = 0.29frsusp_length = 0.29rlsusp_length = 0.755rrsusp_length = 0.755`
Title: Re: Suspension
Post by: Phathry25 on February 09, 2016, 03:06:15 AM
Nevermind, I got it now.  Forgot the old subtract minlenth from restlength trick.  Works as advertised now.  Thanks!
Title: Re: Suspension
Post by: Mace-x on February 10, 2016, 07:41:11 PM
A Buggy!!!!  :o
Fantastic!  ;D